On Christmas Eve, three homeless people in Tokyo—Gin, an alcoholic gambling addict; Hana, a former drag queen; and Miyuki, a runaway teenage girl—find an abandoned newborn baby while searching through garbage bins. They discover a note urging them to care for the infant, as well as a key to a locker. Determined to reunite the baby with her parents, the trio embarks on a journey across the city, relying on their wits and compassion to navigate a variety of challenges. Along the way, their individual backstories and the circumstances that led them to the streets are gradually revealed.

As they follow clues provided by the items found with the baby, Gin, Hana, and Miyuki encounter an array of characters including gangsters, kind-hearted strangers, and old acquaintances. Their search puts them in increasingly difficult situations, testing their resolve and their bond as makeshift guardians. Throughout their adventure, each character also faces their own personal demons and begins to rediscover elements of hope, forgiveness, and redemption.